Tubing set for blood handling system and methods of use

ABSTRACT

A tubing set for use with a blood handling system is described that decreases the priming volume and surface area of the blood handling circuit, lowering the risk of hemodilution, platelet activation, and hemolysis. The tubing set also reduces the number of manual connections required, and uses quick-disconnect couplings to facilitate connections between the various lines, and between the lines and the arterial and venous cannulae.

FIELD OF THE INVENTION

The present invention relates to tubing sets configured for use withblood handling systems.

BACKGROUND OF THE INVENTION

Each year hundreds of thousands of people are afflicted with vasculardiseases, such as arteriosclerosis, that result in cardiac ischemia. Formore than thirty years, such disease, especially of the coronaryarteries, has been treated using open surgical procedures, such ascoronary artery bypass grafting. During such bypass grafting procedures,a sternotomy is performed to gain access to the pericardial sac, thepatient is put on cardiopulmonary bypass, and the heart is stopped usingcardioplegia solution.

Extracorporeal blood handling systems have been developed to oxygenateand circulate the patient's blood while the heart is stopped duringsurgery. Such systems are often complex, comprising several components,such as a blood pump, oxygenator, venous reservoir, heat exchanger,etc., coupled together by tubing. In a typical previously-known bloodhandling system configuration, blood is routed from a patient, e.g. fromthe vena cava or the right atrium, into a venous reservoir, through ablood pump, a heat exchanger, an oxygenator, a filter, and back to thepatient via a cannula placed in the aorta. Each of these components, andthe tubing segments connecting them, requires a minimum fluid volume tooperate and presents a non-native surface area to which the patient'sblood is exposed during operation of the system.

The priming volume of a blood handling system is the volume of fluidneeded to purge all air from the system prior to use, i.e. to prime thesystem, and is equal to the total internal volume of the system. Thepriming fluid, for example, a sterile saline buffered solution with orwithout donor blood products, is typically intermixed with the patient'sblood when the system is in operation. The result is hemodilution, whichcan decrease the concentration of critical blood components toundesirably low levels, or intermix large amounts of donor blood withthe patient's own blood. Donor blood carries with it the risk ofexposure to diseases carried by the blood donor.

Typical previously known blood handling systems have average primingvolumes of approximately 1.8 liters, with median priming volumes ofapproximately 1.9 to 2.0 liters. Adding this amount of fluid can dilutethe 5 liters of blood in the typical adult patient by almost one-third.

The total non-native surface area of a blood handling system is the sumof all surfaces that come into contact with the patient's blood,including the blood-accessible interior spaces of all components, thesurfaces of filters and the oxygenator, and the tubing connecting thepatient to the blood handling system and interconnecting the componentsthereof. It is known that exposure of blood to foreign surfaces isassociated with platelet activation and undesirable clotting, therebytypically requiring the administration of large doses of anti-clottingagents, such as heparin. Despite this known drawback, previously knownblood handling systems typically include approximately 14 m² of internalsurface area.

In addition to the foregoing volume and surface area considerations, thepreparation of previously known blood handling systems by theperfusionist typically requires making eight or more aseptic connectionsbetween the tubing and ports on blood handling system components. Atubing set, as used herein, refers to the segments of tubing andcouplings typically used when connecting components of a cardiopulmonarybypass system.

The tubing and ports fit tightly together, and are often located inawkward and inaccessible locations, making it both physically tiresomeand time consuming to make the required aseptic connections. Moreover,each of these connections represents a potential leak in the system, andair bubbles trapped at the connections can be difficult to dislodge.

Although some blood handling system suppliers have responded to theforegoing problems with pre-assembled tubing sets, these tubing sets aretypically custom made in that the lengths of the various tubingsegments, particularly the perfusion line, are adapted for each specificblood handling system configuration. This requirement for customizationlimits the ability to make a useful standardized pre-assembled tubingset.

For the foregoing reasons, it would be desirable to provide a tubing setfor use with blood handling systems that provides low internal surfacearea and low priming volume, thereby reducing platelet activation,hemolysis and hemodilution. Preferably, such a system would reduce orobviate the need to introduce foreign fluids, such as saline ornon-autologous blood, into the patient's circulation.

It further would be desirable to provide a tubing set for use with bloodhandling systems that requires fewer connections between the tubing setand ports on the blood handling system components, to improve both theease of assembly and the integrity of the system once connected.

It also would be desirable to provide a standardized pre-assembledtubing set that would not need to be customized to the configuration ofeach blood handling system.

SUMMARY OF THE INVENTION

In view of the foregoing, it is an object of the present invention toprovide a tubing set for use with a blood handling system that reducesthe priming volume and internal surface area of the blood handlingsystem, thereby reducing platelet activation, hemolysis andhemodilution.

It is another object of the present invention to provide a tubing setfor use with a blood handling system that reduces the number ofconnections between tubing set and component ports, to facilitateassembly of the circuit including the blood handling system.

It is yet another object of the present invention to provide astandardized pre-assembled tubing set that can be used withinterchangeable perfusion lines of predetermined lengths to adapt to therequirements of the configuration of each particular blood handlingsystem, and the preferences of each clinical team.

These and other objects of the present invention are attained byproviding a tubing set having a length, priming volume and internalsurface area less than half that of tubing sets used in previously knownblood handling systems. More preferably, the tubing set of the presentinvention has a length, priming volume and internal surface area lessthan one quarter of previously known commercial tubing sets.

In a preferred embodiment, the tubing set of the present inventioncomprises two circuits: a perfusion circuit and a priming circuit. Theperfusion circuit couples to the inlet and outlet ports of the bloodhandling system, and includes venous and arterial lines. The venous andarterial lines are connected to each other during initial priming andthereafter may be joined to a perfusion line. During coupling of theblood handling system to the patient, the perfusion line is opened,either by disconnecting a preplaced connector, or by cutting theperfusion line, to create free ends. The free ends then are coupled toarterial and venous cannulae disposed in the patient's blood vessels.The perfusion circuit therefore is used to circulate the patient's bloodto and from the blood handling system during surgery.

The priming circuit of the tubing set couples to the perfusion circuitat locations adjacent to the inlet and outlet ports of the bloodhandling system, and includes an additional tubing segment that permitspriming fluid into the system during initial priming of the system.Priming fluid, which is introduced through a port at the end of thepriming line, is circulated through the blood handling system to primethe system before use and to displace all air and other gasses from thesystem. This prevents the introduction of potential embolism-causing airbubbles into the patient's blood stream. During operation, the primingcircuit also may be used to provide a recirculation loop.

In a preferred embodiment, the tubing set of the present inventioncomprises tubing with an internal diameter of ¼ inch, ⅜ inch, or amixture of both, as compared with the typical previously known systemsthat use tubing with internal diameters of ⅜ inch, ½ inch, or a mixtureof both.

The tubing set of the present invention facilitates standardization byoptionally including one or more quick-disconnect tubing couplings atone or more locations in the blood handling circuit. In a preferredembodiment, quick-disconnect tubing couplings are located at thejunction between the venous and arterial segments of the perfusion lineand at the junction between the venous and arterial lines and thearterial and venous segments of the perfusion line, respectively. Thequick-disconnect tubing connectors at the ends of the perfusion linefacilitate the aseptic connection, disconnection, and reconnection ofthe arterial and venous lines, located outside the sterile field, to theperfusion line located within the sterile field.

The required length of the perfusion line may vary depending on theconfiguration of the blood handling circuit. The quick-disconnect tubingcouplings at the ends of the perfusion line permit rapid, asepticconversion among perfusion lines of various lengths, so that the rest ofthe tubing set may be standardized. The quick-disconnect tubing couplingbetween the ends of the perfusion line also may be used to facilitateaseptic connection of the venous and arterial lines to the venous andarterial cannulae, respectively, disposed in the patient's bloodvessels.

In addition, to further safeguard the sterility of the perfusion line,the tubing set of the present invention may be provided in sterilizeddouble bag packaging. In this configuration, an outer bag thatencompasses the entire tubing set may be opened to reveal a second,sealed inner bag encompassing the perfusion line. This double bagpackaging maintains the sterility of the perfusion line while theperfusionist connects the tubing set to the other components of theblood handling system.

The tubing set of the present invention is especially well-suited forblood handling systems having an active air removal feature, asdescribed in co-pending, commonly assigned, U.S. patent application Ser.No. 09/780,923, filed Feb. 9, 2001. When used in conjunction with theintegrated blood handling system described in that application, theentire blood handling system, including the tubing set of the presentinvention, comprises less than one fifth the volume and one tenth orless of the internal surface area of previously known systems.

When used with a blood handling system having the active air removalsystem described in the aforementioned application, a perfusionist canassemble and prime the blood processing system in a matter of minutes,as opposed to much longer periods required by previously known systems.In addition, that compact integrated blood pump/oxygenator also permitsthe blood handling system to be positioned just outside the sterilefield, thereby reducing the length of the perfusion line required tocouple the blood handling system to the arterial and venous cannulae inthe patient.

The tubing set of the present invention advantageously reduces thenumber of connections between the tubing set and the ports of the bloodhandling system components. When used with the blood handling systemdescribed in the aforementioned application, the tubing set of thepresent invention requires only two connections to ports of the bloodhandling system by the perfusionist: from the venous line to the bloodinlet port of the blood handling system, and from the arterial line tothe blood outlet port of the blood handling system.

Methods of connecting, priming and operating a blood handling systememploying the tubing set of the present invention also are provided.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and advantages of the present invention willbe apparent upon consideration of the following detailed description,taken in conjunction with the accompanying drawings, in which likereference characters refer to like parts throughout, and in which:

FIG. 1 is a schematic diagram of a typical previously known bloodhandling system and tubing set;

FIG. 2 is a schematic diagram of the tubing set of the presentinvention;

FIG. 3 is a schematic diagram showing the tubing set of the presentinvention coupled to an blood handling system after assembly, but priorto connection to a patient's circulatory system;

FIG. 4 is a schematic diagram the blood handling system and tubing setof FIG. 3 after connection to the circulatory system of a patient;

FIG. 5 is an illustration showing the tubing set of the presentinvention sealed in double bag packaging;

FIG. 6 illustrates a potential commercial embodiment of the inventivetubing set; and

FIG. 7 illustrates an exemplary embodiment of a quick-disconnectcoupling suitable for use in the tubing set of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, a typical previously known commercial bloodhandling system 10 is described. System 10 comprises arterial pump 11,oxygenator 12, venous reservoir 13 and arterial filter 14 coupled toeach other by tubing 15. To assemble such a system, the perfusionisttypically removes components 11-14 from separate sterile bags, orseparate compartments of a sterile tub, and then manually attaches thetubing to ports 11 a, 11 b, 12 a, 12 b, 13 a, 13 b and 14 a, 14 b, tointerconnect the components and to form venous line 16 and arterial line17. Blood handling system may in addition include a heat exchanger,recirculation line, etc. (not shown).

Typically, components 11-14 may be pole-mounted or coupled to driveunits disposed in bays of the perfusion station, causing the ports ofthe various components to be awkwardly positioned. In addition, theconventional method of pushing the tubing over barbed or ribbed portscan be quite difficult to accomplish while maintaining these connectionssterile. Venous line 16 is connected to arterial line 17 through theperfusion Line indicated by bold 18 either by connectors or as acontinuum if the sizes of tubing are the same. Venous line 16, includingthat portion of bold line 18 that is on the venous side, as well as thepump portion of tubing 15 used to interconnect these componentstypically consists of ½ inch or even ⅝ inch tubing. This tubing togetherwith arterial line 17 may have an aggregate length of 9 to 12 feet ormore, and therefore a volume of one-half liter or more. The presence ofadditional components, such as a heat exchanger or recirculation linefurther add to the aggregate length, blood-contacting surface area, andpriming volume.

Because the perfusion station typically is several feet distant from theoperating table, it is conventional for the perfusionist to hand-up tothe nurse at the operating table perfusion line, 18 in FIG. 1. Theoutside of all or most of this line is sterile, typically coiled andwrapped within an opaque sterilized bag. Typically, during assembly andpriming of blood handling system 10, the perfusionist will attempt toprime and de-gas the perfusion line along with the balance of the bloodhandling system. In this case, the central portion of perfusion line 18,which is coiled, increases the difficulty in priming and de-gassing theline.

Once the perfusionist adjudges the line to be adequately primed and freeof gas bubbles, the perfusionist opens the sterile bag without touchingthe tubing contained within and allows the coiled mid-section of theperfusion line to be taken up by the nurse at the operating table, whileexercising care not to contact the coil against anything. The nurse thenseparates arterial line 17 from venous line 16 approximately in themiddle of perfusion line 18 by either cutting the perfusion line ordisengaging a connector if used. The nurse and surgeon then attempt tocouple the two free ends thus created to the venous and arterialcannulae disposed in the patient's blood vessels, thereby establishing asterile connection to the venous and arterial cannulae. Alternatively,once the blood handling system is primed and de-gassed, the nurse mayhand-down two separate perfusion lines to the perfusionist that are thencoupled to venous and arterial lines 16 and 17, respectively. Thesurgeon must then wait for adequate de-airing of this line to occurbefore coupling the perfusion line to the cannulae.

The tubing set of the present invention is intended to solve thedifficulties arising in such previously known systems, by facilitatingpriming and de-gassing of the system. In addition, the tubing set of thepresent invention is configured to facilitate interconnection of theblood handling system components while maintaining the sterility of theconnections.

Referring now to FIG. 2, a tubing set constructed in accordance with theprinciples of the present invention is described. Tubing set 20preferably comprises tubing sections arranged to form two main circuits:perfusion circuit 21, comprising lines 22, 23, 23 a, 23 b and 24, andpriming circuit 25 comprising lines 26, 27, 27 a and 27 b. In apreferred embodiment, the tubing employed in perfusion circuit 21 has a⅜ inch inner diameter, while the tubing used in priming circuit 25 has a¼ inch inner diameter. Preferably the tubing of both the perfusioncircuit and priming circuit comprises a biocompatible PVC orsilicone-based polymer.

Perfusion circuit 21 is used to carry venous blood from the patient tothe blood pump and oxygenator, and to return oxygenated blood from theoxygenator to the patient. During use, venous line 22 is coupled at end30 to an inlet port of the blood pump/oxygenator and is coupled usingquick-disconnect coupling half 35 to coupling half 35 of venous segment23 a of perfusion line 23. Venous line 22 may include optional valve 31,which preferably is a pinch clamp (referred to as a “Roberts clamp”).Likewise, in use, arterial line 24 is coupled at end 32 to an outletport of blood pump/oxygenator and is coupled using quick-disconnectcoupling half 36 to coupling half 36′ of arterial segment 23 b ofperfusion line 23. Arterial line 24 also may include optional valve 33.Perfusion line 23 comprises venous segment 23 a and arterial segment 23b joined by optional quick-disconnect coupler 34 having halves 34′ and34″, and preferably includes quick-disconnect coupling halves 35′ and36′ where it joins venous line 22 and arterial line 24, respectively. Anexemplary quick-disconnect coupler is described hereinafter with respectto FIG. 7.

Priming circuit 25 is used for priming the blood pump and oxygenatorduring initial system set-up, and for recirculation and introduction ofdrugs or dilutants to the blood during operation. Line 26 is coupled atend 26 a to venous line 22 of the perfusion circuit near bloodpump/oxygenator inlet end 30, and is coupled at end 26 b to arterialline 24 of the perfusion circuit near blood pump/oxygenator outlet end32. Priming circuit 25 includes priming line 27, which includes suitableconnections on segments 27 a and 27 b for joining those segments to asource of priming fluid, a source of drugs or other therapeutic agents,or a dynamic reservoir. Priming circuit preferably contains valves 37,38 a, 38 b, 39 a and 39 b, to regulate flow through the circuit andpriming line 27. Preferably, all of the valves of tubing set 20 comprisewell-known pinch clamps that engage an exterior surface of the tubing.

In FIG. 3, the tubing set of the present invention is depicted as itwould be configured for use with the integrated blood pump/oxygenatorwith active air removal described in co-pending, commonly assigned U.S.patent application Ser. No. 09/780,923, although a conventional bloodpump and oxygenator coupled together by tubing could be substitutedtherefore.

When the tubing set of the present invention is used with the integratedblood pump/oxygenator described in the aforementioned application, theentire blood handling system can be primed with as little as 400-500 mlof fluid, and has only about 1.4 m² of internal surface area. Bycomparison, typical previously known commercial blood handling systemsrequire about 1.8 liters of priming fluid, and expose blood to about 14m² of foreign surface area. The dramatic reductions in both volume andsurface area facilitated by the tubing set of the present inventionreduce the likelihood of adverse effects from hemodilution, plateletactivation and hemolysis.

Referring to FIGS. 2 and 3, use of blood handling system 40 includingtubing set 20 of the present invention is described. Tubing set 20 isshown connected to blood pump/oxygenator 41 for priming, and in FIG. 3just prior to connection to patient P. Ends 30 and 32 of perfusioncircuit 21 are coupled to inlet port 42 and outlet port 43,respectively, of blood pump/oxygenator 41. Initially, coupling halves 35and 36 are joined together at illustrated in FIG. 2. Priming fluid,preferably buffered saline is stored in collapsible bag 44, which iscoupled, e.g., by spike line, to segment 27 a of priming line 27. Asecond collapsible sterile bag 45 may be coupled to segment 27 b toserve as a dynamic reservoir once bypass flow to the patient has beenestablished, as described hereinafter.

When valves 31, 33, 37, 38 a, 38 b and 39 a are opened, priming fluidenters priming line 27 of the tubing set from bag 44, fills primingcircuit 26, circulates through blood pump/oxygenator 41 and perfusioncircuit 21. In a preferred embodiment, the valves in perfusion circuit21 are initially closed and the bottom of bag 44 is above bloodpump/oxygenator 41. Valve 39 a is opened and the section of tubing abovethe valve deaired. Valve 37 then is opened further, priming line 27. Byopening valve 38 b, the flow of solution can be directed into bloodpump/oxygenator 41 in a reverse direction, resulting in a more gentledisplacement of air up through line 25. Valve 33 (FIG. 2) can be openedfollowed by valve 31 and then valve 38 b to complete the primingcircuit.

Blood pump 41 may be activated to pump the priming fluid throughout thesystem, and the active air removal system, if present, may be actuatedto remove air bubbles from both priming circuit 25 and perfusion circuit21 for venting. Alternatively, manually operable vents may beincorporated in priming circuit 25 and perfusion circuit 21 to permitthe perfusionist to manually vent any air from the system. As a furtheralternative, the perfusion line may be opened at quick-disconnectcoupling 34 to vent any accumulated air in the blood handling system.

Additional valves or vents beyond those specifically described or shownmay be incorporated into any segment of tubing in the tubing set of thepresent invention to improve control over fluid flow and aid in purgingof gas from lines or the blood handling system components. Bloodhandling and treatment components in addition to those shown, e.g., ablood filter or a heat exchanger, may be introduced at locations inblood handling system 40 without deviating from the scope of the presentinvention.

Once the priming fluid has been introduced into the blood handlingsystem from bag 44 and any air removed from the system, valve 39 a isclosed, completing the set-up of the system. When the surgeon is readyto place the patient on cardiac bypass, the perfusionist closes valves31 and 33, and then couples venous line 22 and arterial line 24 toperfusion line segments line 23 a and 23 b using couplings 35, 35′ and36, 36′, respectively, while maintaining coupling 34 intact, as depictedin FIG. 3. Valves 30 and 31 then are opened, and blood pump/oxygenator41 operated to prime perfusion line 23 and flush any air bubbles out ofthe perfusion line. Valves 30 and 31 then are closed, and theperfusionist hands perfusion line 27 up to the nurse at the operatingtable. The nurse receives the center portion of the perfusion line inthe sterile field, uncouples quick-disconnect coupling 34, and couplesthe respective free ends to the arterial and venous cannulae placed inthe patient's blood vessels.

Alternatively, the perfusionist may choose to close valves 31 and 33,and then couple venous line 22 to perfusion line segment 23 a usingcouplings 35 and 35′ while maintaining coupling 34 intact, as depictedin FIG. 3. Valves 31 and 39 a then are opened and the head height of bag44 or the active pump used to slowly prime line 23 just to the end ofcoupling 36′. Coupling 36 and 36′ then are connected and valve 24 openedto complete the priming. Irrespective of sequence selected, the presentinvention allows the complete deairing of a large portion of perfusioncircuit 21 independently of the user preference to pass line 23 up tothe sterile field or vice versa.

As illustrated in FIG. 4, arterial cannula 50 preferably is placed inthe aorta or other suitable location, while venous cannula 51 preferablyis placed in the patient's right atrium, vena cava, or other suitablelocation. When this step is completed, the perfusionist reopens valves31 and 33, permitting blood to be circulated from the patient to theblood handling system and then reperfused into the patient.Quick-disconnect coupling halves 34′ and 34″ facilitate rapid, asepticconnection of venous segment 23 a of perfusion line 23 to venous cannula51 and arterial segment 23 b of perfusion line 23 to arterial cannula50, respectively.

In addition, once the blood handling system is in operation, theperfusionist may close valve 37, while leaving valves 38 a and 38 bopen. This arrangement has the effect of causing a portion of theoxygenated blood exiting into arterial line 24 through outlet port 43and end 32 to be recirculated to inlet port 42 of blood pump/oxygenator41 via line 26 of the priming circuit. Also, if valve 37 is opened whenvalve 38 a closed, a portion of the oxygenated blood exiting throughoutlet port 43 of blood pump/oxygenator 41 will be directed to bag 45,which will thus serve as a dynamic reservoir to temporarily accumulateblood. As a further alternative, the perfusionist may use priming line27 to inject a drug or therapeutic agent, e.g., cardioplegia, into theblood while the perfusion loop is open, to thus directly introduce thedrug or agent into patient's circulation.

Perfusion line 23 also may omit quick-disconnect coupling halves 34′ and34″. In the absence of coupling 34, the surgeon may connect perfusionline 23 to the patient's circulatory system by alcohol sterilizing amid-length of the tubing, aseptically cutting the tubing at that point,and aseptically coupling the resulting free ends to arterial cannula 50and venous cannula 51, in accordance with previously known techniques.

Quick-disconnect coupling halves 35′ and 36′ also facilitate the asepticconnection of perfusion line 23, which is disposed inside the sterilefield, to venous line 22 and arterial line 24, which are disposedoutside the sterile field. In particular, the arrangement of the tubingset of the present invention permits the perfusion circuit and primingcircuit to be manufactured with a single or a few standard lengths,while the perfusion line 23 may be provided in variable lengths to suitspecific operating room configurations and surgical team preferences.Such standardization overcomes a significant shortcoming in previouslyknown attempts to provide customized pre-assembled tubing sets, whichrequired the hospital or clinic to stock a large inventory of entiretubing sets, rather than just the perfusion lines as is possible withpresent invention.

While a blood handling system incorporating the tubing set of thepresent invention will perform the same functions as previously knownblood handling systems, the tubing set of the present invention providesa number of advantages. The low volume and surface area of a bloodhandling circuit including the tubing set of the present inventiondecreases the likelihood of adverse reactions to hemodilution or toexcessive blood contact with non-native surfaces.

The tubing set of the present invention is faster to set up and easierto use, and requires the perfusionist to make only two asepticconnections to the blood handling components. By contrast, previouslyknown commercial blood handling systems require the perfusionist to makeas many as eight or more connections. In such systems, each connectionof a tube to a port must be performed aseptically, and the connectionsare often tight and thus physically difficult to make, especially in theoften awkward locations of the ports. In addition, the low number ofconnections required by the tubing set of the present invention reducesthe number of locations for potential leaks, and for trapping gasbubbles, in the blood handling circuit.

Moreover, when the tubing set of the present invention is used with theintegrated blood pump/oxygenator of the aforementioned patentapplication, only approximately 400 to 500 ml of priming fluid arerequired. Because an average adult patient has about 5 liters of blood,the patient's own blood may be used to prime the blood handling system,thus obviating the need for donor blood or saline. By comparison,previously known blood handling systems require about 1.8 liters ofpriming fluid, and thus increase the volume of the fluid in thepatient's circulatory system by about one-third.

In the case where the perfusionist desires to use the patient's ownblood to prime the blood handling system comprising the tubing set andintegrated blood pump/oxygenator of the aforementioned patentapplication, the blood handling system 40 is still initially primed withsaline until all air bubbles are removed from all lines and theintegrated blood pump/oxygenator 41.

Once the blood pump is coupled to the arterial and venous cannulae,however, the patient's blood may be used to displace the saline, e.g.,by directing the saline via valves 33, 38 a, 38 b, 37 and 39 b to bag45, which acts as a dynamic reservoir. When the patient's blood beginsto enter arterial line 24, valves 31, 37, 38 a and 39 b are opened andvalves 33 and 38 a are closed. This procedure allows the perfusionist toprime the extracorporeal blood handling system 26 with saline, and yetnever introduce the bulk of the prime saline into the patient'scirculation, thus reducing hemodilution. Blood may be drawn from thepatient to the blood handling system either by operation of bloodpump/oxygenator 41, or more preferably, simply under the pressureprovided in the patient's vessels. As will be apparent to one of skillin the art, a different arrangement of the foregoing valves may be made,so that the patient's blood is drawn into the system in a retrogrademanner via arterial line 24, rather than venous line 22.

Referring now to FIG. 5, tubing set 20 of the present invention isdescribed as packaged for commercial use. Tubing set 20 is enclosed inouter sterile bag 60, with perfusion line 23 (including quick-disconnectcoupling 34, if provided) enclosed in inner sterile bag 65 with couplinghalves 34′ and 34″ extending outside sterile inner bag 65. Thisarrangement permits the ends of segments 23 a and 23 b of perfusion line23 to be manipulated and coupled to venous line 22 and arterial line 24of the tubing set, while maintaining the sterility of the mid-region ofperfusion line, which is handed-up to the sterile field. Tubing set 20may be sterilized by auto-claving, irradiated, or more preferably issterilized by exposure to ethylene oxide.

Referring to FIG. 6, an illustrative potential commercial embodiment ofa tubing set constructed in accordance with the present invention isdescribed. Tubing set 70 is shown coupled to integrated bloodpump/oxygenator 100, which is described in detail in the aforementionedpatent application. Tubing set 70 includes perfusion circuit 71,comprising venous line 72, perfusion line segments 73 a, 73 b andarterial line 74, and priming circuit 75 comprising line 76, primingline 77, and segments 77 a and 77 b. The ends of perfusion line segments73 a and 73 b are shown extending into the sterile field as they wouldappear during use.

Tubing set 70 illustratively includes pinch clamps 78 and samplingmanifolds 79 disposed on various of the lines. Quick-disconnectcouplings 80 are shown are the junctions of venous line 72 and venoussegment of perfusion line 73 a and arterial line 74 and arterial segmentof perfusion line 73 b. As shown in the inset in FIG. 6, thequick-disconnect couplings permit venous line 72 to be directly coupledto arterial line 74 during the priming step. In addition, anotherquick-disconnect coupling 81 is provided in line 76 to permit, forexample, the inclusion of a heat exchanger when the priming circuit isused for recirculation.

With respect to FIG. 7, illustrative quick-disconnect coupling 85 isdescribed. Coupling 85 preferably comprises an rigid material such asacrylic, ABS, polysulfone or polycarbonate material and includes maleportion 86 and female portion 87 that snap fit together to provide afluid-tight seal. Male portion 86 includes silicone O-ring 88 and barb89 for coupling to tubing. Female portion 87 includes barb 90 andrelease knob 91. Quick-disconnect couplings of the type illustrated inFIG. 7 are available from Colder Products Company, St. Paul, Minn.,under the MPC and MPX Series connectors, although one of skill in theart will recognize that other types of quick-disconnect couplings alsoare suitable for use in the tubing set of the present invention.

Although preferred illustrative embodiments of the present invention aredescribed above, it will be evident to one skilled in the art thatvarious changes and modifications may be made without departing from theinvention. It is intended that the appended claims cover all suchchanges and modifications that fall within the true spirit and scope ofthe invention.

1. A method of priming and using a blood handling system comprising:providing a blood pump/oxygenator; providing a tubing set having aperfusion circuit and a priming circuit, the perfusion circuit includinga venous line, an arterial line, and a perfusion line coupled to thevenous line and the arterial line, the priming circuit including a firstend coupled to the venous line, a second end coupled to the arterialline and a priming line; providing a source of priming fluid; coupling afree end of the venous line to an inlet of the blood pump/oxygenator;coupling a free end of the arterial line to an outlet of the bloodpump/oxygenator; coupling the priming line to the source of primingfluid; releasing the priming fluid into the priming line, so that thepriming fluid fills the priming circuit, the perfusion circuit and theblood pump/oxygenator; and operating the blood pump/oxygenator toaccumulate and vent air from the blood handling system.
 2. The method ofclaim 1 further comprising: after accumulating and venting air from theblood handling system, separating the perfusion line to form a firstsegment coupled to the venous line having a first free end and a secondsegment coupled to the arterial line having a second free end; couplingthe first free end to a venous cannula disposed in a patient; andcoupling the second free end to an arterial cannula disposed in thepatient.
 3. The method of claim 2, further comprising: clamping thearterial line; drawing blood from the patient into the blood handlingsystem to displace the priming fluid through the priming line into thesource of priming fluid; and clamping the priming line; and unclampingthe arterial line to establish cardiopulmonary bypass flow through theblood handling system.
 4. The method of claim 2, further comprising:clamping the venous line; drawing blood from the patient into the bloodhandling system to displace the priming fluid through the priming lineinto the source of priming fluid; and clamping the priming line; andunclamping the venous line to establish cardiopulmonary bypass flowthrough the blood handling system.
 5. The method of claim 1 whereinseparating the perfusion line comprises disconnecting a quick-disconnectcoupling disposed in the perfusion line.
 6. The method of claim 5,further comprising regulating flow through the priming circuit torecirculate a portion of a flow passing through the arterial line to thevenous line.